Types Of Failures In Beam:
There are mainly two types of failures in beam.
- Shear failure.
- Flexural failure.
When the shear stress on an object exceeds the maximum permissible shear stress, then the object undergoes a failure known as shear failure. Shear failure can be defined as a failure that takes place due to insufficiency of shear resistance available between the materials.
Shear strength is the strength of a material or component against the type of yield or structural failure where the material or component fails in shear.
A shear load is a force that tends to produce a sliding failure on a material along a plane that is parallel to the direction of the force.
In simple words, shear stress is maximum at 45° in cross-section of beam hence diagonal crack is formed in shear failure and shear failure occurs at the end of the beam where the beam connects to the column. To avoid this type of failure stirrups are provided.
Shear failure can be easily determined by checking out the excessive deflection or development of cracks, which gives an advance warning about the probable occurrence of shear failure.
It is difficult to understand the extent to which reinforcement will act along with concrete, and predict the actual time of occurrence of shear failure.
The figure shown below shows the shear failure in the beam.
Causes Of Shear Failure:
The reasons behind shear failure are-
• It may occur due to insufficient knowledge of the resistance between reinforced steel rods and concrete columns.
• It may occur due to the wrong interpretation of the data made available to the design engineer.
• It may also take place due to insufficient strength of the concrete used for the structure.
• It may even take place due to mismatch in the positioning of the reinforcement of steel rods.
Flexural strength, also known as modulus of rupture, bend strength, or fracture strength, is a material property, defined as the stress in a material just before it yields in a flexure test.
The flexural strength represents the highest stress experienced within the material at its moment of rupture. It is measured in terms of stress. To overcome this type of failure, main steel is provided at the bottom/top of the beam. Flexural failure occurs at mid-span of beam.
Flexural failures are two types.
- Brittle flexural failure and
- Ductile flexure failure.
Brittle Flexure Failure:
The brittle flexural failure is characterized by the crushing of concrete before the rebar yields and it’s very acute because it doesn’t give warning to the residents or the users of the structure. This kind of failure generally happens to over reinforced section.
Ductile Flexure Failure:
The Ductile flexural failure is characterized by the failure of rebar before the concrete and it usually happens with large deformation when the rebar is a character of under reinforced sections.
The other failure is due to shear stress and when the members are located at the outer sides of the structure, torsional failure is also possible.
Tags: Beam Failures, Types Of Failures In Beam.